The present invention relates to an automatic transmission.
As a technique for judging an occurrence of interlock of an automatic transmission, for example, it is disclosed in Japanese Patent Provisional Publication No. 2008-232355 (hereinafter is referred to as “JP2008-232355”). JP2008-232355 discloses an interlock judgment technique in which, when deceleration of a vehicle is greater than or equal to a predetermined deceleration also an actual gear ratio determined from an input revolution speed and an output revolution speed of an automatic transmission is out of a predetermined range that is set on the basis of a gear ratio of a speed that is currently commanded or instructed, it is judged that the interlock occurs.